Whoa, plot twist! Didn't see that one coming.
I love a good surprise.
I'm not a fan of cold calling in general, but especially with the plan to bluff. I find it is too risky especially with the chance of the original raiser putting more in.
Flop seems okay to float since sizing is so small. Turn, I would not bet this small as a bluff. Given that you played the way you did to this point, river sizing seems good.
The problem with using this scenario to determine if this is a good bluff or not is the fact that 88 is near the bottom of your opponent's range. Sometimes he's going to have AQ, AK, QQ, KK, etc... where he isn't going to fold. Either he's calling with 88 because he is a station, or he notices you are tilting and is exploiting you.
Given that you know he has exactly 88 and with him not being aware of this knowledge, it is a good bluff, but you didn't know this until after the hand was over.
Since you are exploiting with air, you need your opponent to be overfolding and not overcalling.